Collaborative Research: Testing hypotheses of latest Pleistocene paleo-environmental collapse, Northern Channel Islands, California

测试晚更新世古环境崩溃的假说，北方海峡群岛，加利福尼亚州这项研究将描述戏剧性的古环境变化的性质和时间发生在北方海峡群岛（NCI）的加州州在最新更新世。 特别是，我们将测试的主要假设，即砍伐森林的岛屿，河流加积，滑坡，和广泛的燃烧是同步事件引起的急剧变化火制度-每一个硅氧烷与第一个人类的到来和猛犸象的灭绝。 其他次要假设将进行测试，包括气候变化引起的变化，逐渐气候驱动的火灾频率增加，由于海平面上升，或在13万年的影响事件，生态系统减少。最近对NCI的研究发现，在13，00 cal yBP左右的关键事件的年龄越来越趋同，包括（1）古植物学从针叶林覆盖到非乔木植被的转变，（2）低地加积的开始，（3）更新世滑坡：（4）木炭和弥散碳的沉积;（5）第一批人类的到来，以及（6）猛犸象在NCI上的灭绝。 另一个研究小组认为撞击事件发生在约12.9 ka。 这项工作将测试这些假设，通过：最新更新世序列，光释光和放射性碳测年，孢粉学和古植物学，后OIS 2海侵的本地绘图，木炭沉积的特性，以及通过最新更新世-全新世序列的微球体和其他潜在的外星指示器的系统采样的地层学的详细描述。 火是一种记录在案的机制，少数人可能会对自然系统产生巨大影响。 区域人类活动对环境的影响是人类向新世界迁移的先锋，这可能意味着一种以前没有认识到的时间和规模。

Testing a Hypothesis of Latest Pleistocene Paleo-environmental Collapse, Northern Channel Islands, CaliforniaThis research will describe the nature and timing of dramatic paleo-environmental changes that occurred on the Northern Channel Islands (NCI) of California during the latest Pleistocene. In particular, we will test the primary hypothesis that deforestation of the islands, fluvial aggradations, landsliding, and widespread burning were synchronous events caused by a sharp change in fire regime - per haps associated with the arrival of the first humans and the extinction of mammoths. Other secondary hypotheses will be tested, including changes caused by gradual climate change, gradual climate-driven increases in fire frequency, ecosystem reduction due to sea-level rise, or an impact event at ~13ka. Recent research on the NCI has seen a growing convergence in the ages of key events around 13, 00 cal yBP, including (1) a paleobotanical shift from conifer cover to non-arboreal vegetation, (2) onset of lowland aggradations, (3) Pleistocene landsliding: (4) deposition of charcoal and disseminated carbon; (5) arrival of the first humans, and (6) extinction of mammoths on the NCI. Another research group has suggested an impact event at ~12.9 ka. This work will test these hypotheses through: detailed description of the stratigraphy of latest Pleistocene sequences, OSL and radiocarbon dating, palynology and paleobotany, local mapping of the post-OIS2 transgression, characterization of charcoal deposition, and systematic sampling of microspherules and other potential extraterrestrial indicators through the latest Pleistocene-Holocene sequence. Fire is a documented mechanism by which small numbers of humans may have large impacts on natural systems. Regional anthropogenic environmental impacts at the vanguard of human migration into the New World might imply a timing and magnitude not previously recognized.